Zero-gravity venting of three refrigerants

An experimental investigation of venting cylindrical containers partially filled with initially saturated liquids under zero-gravity conditions was conducted in the NASA Lewis Research Center 5-second zero-gravity facility. The effect of interfacial mass transfer on the ullage pressure response during venting was analytically determined, based on a conduction analysis applied to an infinitely planer (flat) liquid-vapor interface. This pressure response was compared with both the experimental results and an adiabatic decompression computation

The effect of the GLP-1 analogue Exenatide on functional connectivity within an NTS-based network in women with and without obesity.

ObjectiveThe differential effect of GLP-1 agonist Exenatide on functional connectivity of the nucleus tractus solitaries (NTS), a key region associated with homeostasis, and on appetite-related behaviours was investigated in women with normal weight compared with women with obesity.MethodsFollowing an 8-h fast, 19 female subjects (11 lean, 8 obese) participated in a 2-d double blind crossover study. Subjects underwent functional magnetic resonance imaging at fast and 30-min post subcutaneous injection of 5 μg of Exenatide or placebo. Functional connectivity was examined with the NTS. Drug-induced functional connectivity changes within and between groups and correlations with appetite measures were examined in a region of interest approach focusing on the thalamus and hypothalamus.ResultsWomen with obesity reported less hunger after drug injection. Exenatide administration increased functional connectivity of the left NTS with the left thalamus and hypothalamus in the obese group only and increased the correlation between NTS functional connectivity and hunger scores in all subjects, but more so in the obese.ConclusionsObesity can impact the effects of Exenatide on brain connectivity, specifically in the NTS and is linked to changes in appetite control. This has implications for the use of GLP-1 analogues in therapeutic interventions

Altered functional connectivity within the central reward network in overweight and obese women.

Background/objectivesNeuroimaging studies in obese subjects have identified abnormal activation of key regions of central reward circuits, including the nucleus accumbens (NAcc), in response to food-related stimuli. We aimed to examine whether women with elevated body mass index (BMI) show structural and resting state (RS) functional connectivity alterations within regions of the reward network.Subjects/methodsFifty healthy, premenopausal women, 19 overweight and obese (high BMI=26-38 kg m(-2)) and 31 lean (BMI=19-25 kg m(-2)) were selected from the University of California Los Angeles' Oppenheimer Center for Neurobiology of Stress database. Structural and RS functional scans were collected. Group differences in grey matter volume (GMV) of the NAcc, oscillation dynamics of intrinsic brain activity and functional connectivity of the NAcc to regions within the reward network were examined.ResultsGMV of the left NAcc was significantly greater in the high BMI group than in the lean group (P=0.031). Altered frequency distributions were observed in women with high BMI compared with lean group in the left NAcc (P=0.009) in a medium-frequency (MF) band, and in bilateral anterior cingulate cortex (ACC) (P=0.014, <0.001) and ventro-medial prefrontal cortex (vmPFC) (P=0.034, <0.001) in a high-frequency band. Subjects with high BMI had greater connectivity of the left NAcc with bilateral ACC (P=0.024) and right vmPFC (P=0.032) in a MF band and with the left ACC (P=0.03) in a high frequency band.ConclusionsOverweight and obese women in the absence of food-related stimuli show significant structural and functional alterations within regions of reward-related brain networks, which may have a role in altered ingestive behaviors

Sintering and Properties of Sintered ZnTiO3

Ultrаfini prаh cink-mеtаtitаnаtа vеličinе čеsticа 40 dо 80 nm pоdvrgnut је prilikоm sintеtskоg dеlа trеtmаnа uticајimа pritiskа i tеmpеrаturе kоrišćеnjеm prоcеsа prеsоvаnjа i rеаkciоnоg sintеrоvаnjа. S оbzirоm nа nеstаbilnоst prаhа pоsmаtrаn је оdgоvоr sistеmа nа оvа dvа trеtmаnа. Uslеd nаvеdеnih uticаја dоšlо је dо spеcifičnih prоmеnа svојstаvа isprеsаkа i sintеrоvаnih uzоrаkа. Štо sе prеsоvаnjа tičе urаđеn је sеt isprеsаkа kоmpаktirаnih nа rаzličitim pritiscimа uniаksiјаlnim dvоstrаnim nаčinоm prеsоvаnjа. Меtоdе kаrаktеrizаciје isprеsаkа kоје su kоrišćеnе su: mеrеnjе gustinе isprеsаkа, mеrеnjе spеcifičnе pоvršinе mеtоdоm аdsоrpciје аzоtа nа niskim tеmpеrаturаmа, оdrеđivаnjе pоrоznоsti mеtоdоm živinе pоrоzimеtriје. Zа оpisivаnjе fеnоmеnа prеsоvаnjа upоrеđеnе su еkspеrimеntаlnе vrеdnоsti gustinе isprеsаkа u zаvisnоsti оd pritiskа prеsоvаnjа sа јеdnаčinаmа kоmprеsibilnоsti. Pritisаk оd 98 MPa оdrеđеn је kао nајpоgоdniјi pri kоmpаktirаnju isprеsаkа zа nаrеdni prоcеs sintеrоvаnjа. Urаđеnа је rеndgеnоstrukturnа аnаlizа kао i аtоmskа mikrоskоpiја isprеskа cink-mеtаtitаnаtа ZnTiO3. Prоcеs sintеrоvаnjа prаćеn је tеhnikоm dilаtоmеtriје, оdnоsnо linеаrnоg skuplјаnjа uzоrаkа pri zаgrеvаnju. Rаđеnо је u dvа rеžimа rаdа dо 880°C i dо 1200°C. Zа rеžim rаdа pri zаgrеvаnju dо 880°C zа sintеrоvаnjе оdrеđеnа је еnеrgiја аktivаciје sintеrоvаnjа. Urаđеnа је rеndgеnоstrukturnа аnаlizа sintеrоvаnih uzоrаkа, i nа оsnоvu rаzličitоg fаznоg sаstаvа dоkаzаnо pоstојаnjе fаznоg prеlаzа u stаbilniјu fоrmu spinеlskе strukturе, cink-оrtоtitаnаt, Zn2TiO4. Dilаtоmеtriја kао оsnоvnа tеhnikа zа prаćеnjе prоcеsа sintеrоvаnjа је pоkаzаlа dа pri grејаnju nа višој tеmpеrаturi dоlаzi dо fаznоg prеlаzа. Strukturа sintеrоvаnih uzоrаkа оkаrаktеrisаnа је tаkоđе mеtоdоm аtоmskе mikrоskоpiје i uоčеnа rаzlikа u vеličini zrnа zа rаzličitе rеžimе grејаnjа.Zinc meta-titanate ZnTiO3 nano powder commercially available with particle size in a range from 40 nm to 80 nm was treated by conventional synthesis methods, namely, the compaction and the sintering. According to instability of the powder, response of the system to these two fundamental treatments was studied. Regarding used methods, changes in properties of the compacts and sintered specimens occurred. Uniaxial double sided compaction method produced set of green bodies obtained using different pressures. Employed characterization methods used were: density measurements, specific surface area measurements by nitrogen adsorption on low temperatures, porosity measurements with mercury porosimetry. For the compressibility phenomenon different compaction equations were used in order to mathematically describe compaction. Compacts obtained with 98 MPa pressure were determined as suitable for consequent sintering process. X-ray diffraction was conducted on green body of the commercial ZnTiO3 powder. Also, compact was characterized with atomic force microscopy. Sintering process was characterized with fundamental technique for following a linear change in dimensions, namely high temperature dilatometry. Experiments were conducted in two different isothermal temperatures: lower at 880°C and higher at 1200°C. For the lower temperature region of 880°C activation energy calculation was performed. Dilatometry as main technique for following of the sintering phenomenon registered at higher temperature region of 1200oC, phase transition to stabile zinc-orthotitanate spinel Zn2TiO4. Phase transition was justified with X-ray diffraction of specimens heated on 880°C showed characteristic perovskite ZnTiO3 structure diffractogram, while specimen heated at 1200°C gave spinel Zn2TiO4 characteristic diffraction patterns. Sintered specimens in two regimes were characterized with atomic force microscopy also, and significant difference between grain sizes was detected

A Framework for Establishing Restoration Goals for Contaminated Ecosystems

This article represents 1 of 6 articles in the special series “Restoration of Impaired Ecosystems: An Ounce of Prevention or a Pound of Cure?” The articles result from a Technical Workshop organized by SETAC and the Society for Ecological Restoration, held June 2014 in Jackson, Wyoming, that focused on advancing the practice of restoring ecosystems that have been contaminated or impaired from industrial activities.As natural resources become increasingly limited, the value of restoring contaminated sites, both terrestrial and aquatic, becomes increasingly apparent. Traditionally, goals for remediation have been set before any consideration of goals for ecological restoration. The goals for remediation have focused on removing or limiting contamination whereas restoration goals have targeted the ultimate end use. Here, we present a framework for developing a comprehensive set of achievable goals for ecological restoration of contaminated sites to be used in concert with determining goals for remediation. This framework was developed during a Society of Environmental Toxicology and Chemistry (SETAC) and Society of Ecological Restoration (SER) cosponsored workshop that brought together experts from multiple countries. Although most members were from North America, this framework is designed for use internationally. We discuss the integration of establishing goals for both contaminant remediation and overall restoration, and the need to include both the restoration of ecological and socio-cultural-economic value in the context of contaminated sites. Although recognizing that in some countries there may be regulatory issues associated with contaminants and clean up, landscape setting and social drivers can inform the restoration goals. We provide a decision tree support tool to guide the establishment of restoration goals for contaminated ecosystems. The overall intent of this decision tree is to provide a framework for goal setting and to identify outcomes achievable given the contamination present at a site. Integr Environ Assess Manag 2016;12:264–272. 2015 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC

Influence of Tool Geometry and Process Parameters on the Properties of Friction Stir Spot Welded Multiple (AA 5754 H111) Aluminium Sheets.

Friction stir spot welding is an emerging spot-welding technology that offers opportunities for joining a wide range of materials with minimum energy consumption. To increase productivity, the present work addresses production challenges and aims to find solutions for the lap-welding of multiple ultrathin sheets with maximum productivity. Two convex tools with different edge radii were used to weld four ultrathin sheets of AA5754-H111 alloy each with 0.3 mm thickness. To understand the influence of tool geometries and process parameters, coefficient of friction (CoF), microstructure and mechanical properties obtained with the Vickers microhardness test and the small punch test were analysed. A scanning acoustic microscope was used to assess weld quality. It was found that the increase of tool radius from 15 to 22.5 mm reduced the dwell time by a factor of three. Samples welded with a specific tool were seen to have no delamination and improved mechanical properties due to longer stirring time. The rotational speed was found to be the most influential parameter in governing the weld shape, CoF, microstructure, microhardness and weld efficiency. Low rotational speeds caused a 14.4% and 12.8% improvement in joint efficiency compared to high rotational speeds for both tools used in this investigation

ZnTiO3 Ceramic Nanopowder Microstructure Changes During Compaction

ZnTiO3 nanopowder as a constitutive component in compact production was primarily characterised. Scanning electron micrographs of as received powder were recorded. Mercury porosimetry and nitrogen adsorption were also performed on loose powder. Particle size distribution in a water powder suspension was determined with a laser particle size analyser. Compaction was performed on different pressures in a range from 100 to 400 MPa using the uniaxial double sided compaction technique without binder and lubricant. Micrographs of compacted specimens were obtained using scanning electron microscopy and atomic force microscopy. Pore size distribution was also determined by mercury porosimetry and nitrogen adsorption. Results revealed that with increasing pressure during compaction interagglomerate pores diminish in size until they reach some critical diameter related to the intra-agglomerate pore size

Analysis of the initial-stage sintering of mechanically activated SrTiO3

The initial-stage of sintering plays a significant role in determining the final microstructure that defines the main characteristics of electroceramics materials such as functional properties. In this article non-isothermal sintering of non-activated and mechanically activated SrTiO3 samples was investigated up to 1300 °C. Dilatometric curves indicate that mechanical activation leads to an earlier onset of sintering, suggesting that it should lead to a more homogenous and denser sintered product. Analysis of the initial stage of sintering reveals that the sintering process of all examinated samples consists of two or three overlapping single-step processes, with a change in the dominant mass transport mechanism. The values of apparent activation energy of the considered single-step process exhibit a significant decrease with an increase in mechanical activation time. The values of the density of samples after isothermal sintering indicate that the final stage of sintering has not been reached by 1300 °C

Antibiotic Resistance Patterns of Bacterial Isolates from Blood in San Francisco County, California, 1996-1999

Countywide antibiotic resistance patterns may provide additional information from that obtained from national sampling or individual hospitals. We reviewed susceptibility patterns of selected bacterial strains isolated from blood in San Francisco County from January 1996 to March 1999. We found substantial hospital-to-hospital variability in proportional resistance to antibiotics in multiple organisms. This variability was not correlated with hospital indices such as number of intensive care unit or total beds, annual admissions, or average length of stay. We also found a significant increase in methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and proportional resistance to multiple antipseudomonal antibiotics. We describe the utility, difficulties, and limitations of countywide surveillance

Analysis of the Initial-Stage Sintering of Mechanically Activated SrTiO3

The initial-stage of sintering plays a significant role in determining the final microstructure that defines the main characteristics of electroceramics materials such as functional properties. In this article non-isothermal sintering of non-activated and mechanically activated SrTiO3 samples was investigated up to 1300 degrees C. Dilatometric curves indicate that mechanical activation leads to an earlier onset of sintering, suggesting that it should lead to a more homogenous and denser sintered product. Analysis of the initial stage of sintering reveals that the sintering process of all examinated samples consists of two or three overlapping single-step processes, with a change in the dominant mass transport mechanism. The values of apparent activation energy of the considered single-step process exhibit a significant decrease with an increase in mechanical activation time. The values of the density of samples after isothermal sintering indicate that the final stage of sintering has not been reached by 1300 degrees C